An impedance and multi-wavelength near-infrared spectroscopy IC for non-invasive blood glucose estimation

A multi-modal spectroscopy IC combining the impedance spectroscopy (IMPS) and the multi-wavelength near-infrared spectroscopy (mNIRS) is proposed for high precision non-invasive glucose level estimation. A frequency sweep (10kHz - 76kHz) sinusoidal oscillator (FSSO) is proposed for high resolution (500 steps) for IMPS. The output voltage swing of the FSSO is stabilized by an adaptive gain control (AGC). The measurement results of the IMPS and mNIRS are combined by an artificial neural network (ANN) in external smart device so that mean absolute relative difference (mARD) is enhanced to 8.3% from 15% of IMPS, 15% - 20% of mNIRS. A proposed 12.5mm2 0.18μm CMOS chip consumes peak power of 38mW at 1.5V.